BibTeX

@ARTICLE{iumj12046,
    author = "Eberhard Hopf",
     title = "An Inequality for Positive Linear Integral Operators",
   journal = "Indiana Univ. Math. J.",
  fjournal = "Indiana University Mathematics Journal",
    volume = 12,
      year = 1963,
     issue = 5,
     pages = "683--692",
      issn = "0022-2518",
     coden = "IUMJAB",
   mrclass = "",
}

amsrefs

\bib{iumj12046}{article}{
     author = {Hopf, Eberhard},
      title = {An Inequality for Positive Linear Integral Operators},
    journal = {Indiana Univ. Math. J.},
     volume = {12},
       year = {1963},
     number = {5},
      pages = {683 \ndash 692},
}